This Invention relates to a generic external cooling device for laptop computers, and for cases of computers.
Laptop computers contain heat-producing components such as microprocessors, batteries, and DVD/CDROM drives in a small space. When the laptop is in use, these components heat up the air inside the laptop. Some laptop manufacturers accommodate this by providing vents for air exchange on the base of the laptop chassis.
However, laptops are often used on tables/desks, sofas, beds and even floors. These work surfaces are usually made of materials of low thermal conductivity such as wood, plastics, lacquer, cloth or carpet.
When such laptops are in use, the heat generating components continuously heat up the air inside, which flows out of the vents onto insulating surfaces. Therefore transfer of heat from the laptop is hindered.
Furthermore, some laptops have only small vents, or no vents, on the base of the chassis which leads to even less heat loss, so the actual base of the chassis itself heats up.
The base area of the laptop is relatively large with respect to the size of the laptop, so using it on surfaces with high thermal resistivity reduces the possibility of significant heat transfer from the laptop by virtue of surface area.
As heat is continuously produced while the laptop is in use, heat builds up inside the laptop.
Therefore using laptops on surfaces of low thermal conductivity causes the laptop to heat up. This can cause the laptop to overheat, thereby slowing it down and/or causing it to xe2x80x98crashxe2x80x99. The faster a CPU has to work, the more heat it generates. When a laptop is used at maximum capacity, e.g. working with large sized graphic files or watching DVD multimedia, the continuous production of heat from components can make prolonged use uncomfortable if the laptop is held on a lap.
Consumer demand for mobile computing dictates a trend to produce smaller, sleeker laptops with higher speed CPUs, larger RAMs and built in DVD ROMS. This results in the production of laptops with higher heat generating components in smaller casings. This exacerbates the problem of heat build up in the laptop, as there is less air surrounding components that produce more heat during usage.
There have been several inventions that address the problem of the heat generated within laptops. So far the solutions provided suffer from a number of disadvantages.
U.S. Pat. No. 5,969,939 to Moss, et al., (1999) is designed to cool the laptop computer while it is attached to a docking station, so that a surface of the computer is in engagement with a heat conductive surface. This means that the laptop is only cooled while in use with its docking station, therefore partially reducing the advantages of mobility. A docking station is intended for use on a table and not on a lap, sofa or bed, or while in transit. Furthermore, heat transfer by conduction is only effective if the conductive surfaces are flush in tight contact with each other, to aid thermal conduction from the computer chassis to the conductive surface.
U.S. Pat. No. 5,982,615 to Song (1999) attempts to increase heat loss via air ventilation holes formed on the keyboard. This method not only requires the development of such a keyboard, but also providing more apertures allows more dust to enter the laptop.
U.S. Pat. No. 5,936,836 to Scholder (1999) uses a fan to direct airflow over the heat sink in order to remove heat from the heat sink. The running of this extra fan to induce airflow over the heat sink will draw on battery power.
U.S. Pat. No. 5,978,228 to Borkar, et al., (1999), provides an apparatus to mount a very large scale integration (VSLI) chip, such as the microprocessor, on the chassis of the computer system, in order to dissipate heat from the VSLI chip to the outside through the computer chassis. As described earlier, most work surfaces are made of low conductivity material, and using such a computer on insulting surfaces will reduce the effectiveness of heat dissipated through the computer chassis. A heated chassis may not be comfortable when the laptop is used on a lap.
Several Patents such as U.S. Pat. No. 5,822,187 to Thermal Corp (1998), U.S. Pat. No. 5,910,883 to IBM (1999), U.S. Pat. No. 5,818,693 to Thermal Corp (1998), U.S. Pat. No. 5,966,286 to O""Conner, et al., Patent WO 99/10797 to Intel Corp (US) (1999), use a system of heat pipes to cool the laptop. Other Patents such as DE 4244743 to Toshiba Kawasaki KK (1995), U.S. Pat. No. 5,634,351 to Aavid Lab Inc (1997), U.S. Pat. No. 5,606,341 to NCR Corp (1997) and U.S. Pat. No. 5,826,643 to Gaylon, et al (1998) require the use of liquid coolants within the laptop to aid in heat loss. These solutions require a system of ducts, pipes or bags of flexible film that contain the coolant for evaporation and condensation. therefore entailing specific incorporation inside the laptop, and reducing housing space in the laptop, which can otherwise be used for components. These methods also add to the weight of the laptop, and possible increase in size of the chassis.
One commercially-available cooling device is a stand for laptops comprising a pair of mutually rotatable sheets of plastics material. The upper sheet has a pair of protrusions near one edge so that the laptop may be raised at a slight slant, leaving a small space between. Some cooling Is achieved, but this Is only temporary and, on extended use, the temperature within the laptop will exhibit a considerable increase.
Among the objects of the present invention are:
(a) To provide heat transfer from the laptop without requiring it to be attached to an immobile structure which in part defeats the purpose of mobile computing.
(b) To provide heat transfer from the laptop without the need for more apertures, thus decreasing the exposure of internal components to dust.
(c) To provide heat transfer from the laptop without the need to draw power from the mains or battery.
(d) To improve heat transfer from the laptop via the chassis, and allow a heated chassis to be comfortably used on a lap.
(e) To provide heat transfer from the laptop, without adding more apparatus or components to the limited space available within the casing, or adding extra weight to the laptop itself.
Further objects and advantages are to provide a laptop cooling device, which can be easily and conveniently, used without internal alterations to the laptop itself.
One embodiment of the invention provides external cooling equipment for cooling laptop computers which comprises a support for raising a laptop above a working surface for the laptop, said support having an upper surface distributed over at least two levels whereby it contacts the base of the laptop over only a part of said base, permitting the free passage of air across the support and between the laptop and the support, said support being formed from a material of high thermal conductivity, with a surface adapted for rapid transfer of heat between the material and air passing over said surface.
Another embodiment of the invention provides external cooling equipment for cooling computer cases which comprises a material adapted to fit round the casing of a computer unit, contacting the casing over only a part thereof, permitting the free passage of air across the computer casing and between the casing and the equipment, said equipment being formed from a material of high thermal conductivity, with a surface adapted for rapid transfer of heat between the material and air passing over said surface.
As the invention aids the dissipation of the heat built up in the laptop without the need specific design and integration within the computer, it is relatively less expensive to produce. Due to its generic nature, it is suitable for use with existing laptops without internal modifications such that any laptop owner can use it.